Three-cylinder tandem engine



March 1933. R. E. BRUCKNER 1,900,858

I THREE-CYLINDER TANDEM ENGINE Filed Feb. 9, 1929 2 Sheets-sheaf. 1

All

avwentoz ROBERT E. BfiUC/f/VER March 7, 1933. R E BRUCKNER 1,900,858

THREE-CYLINDER TANDEM ENGINE Filed Feb. 9, 1929 2 Sheets-Sheet 2 fi 6 gum/"box ROBERT E. BRUC/f/YER 831 his Gbto'mw 764 a 2 Patented Mar. 7, 1933 UNITED STATES PATENT OFFICE ROBERT 'EARLL BRUcKnER, or EAs'roN, PENNSYLVANIA, ASSIGNOR TO 'DOHIERTY RESEARCH cor/mm, or NEW YORK, N. Y., A CORPORATION OF DELAWARE THREECYLINDER TANDEM ENGINE Application filed February 9.19%. Serial No. 338,840.

The present invention relates tointernal combustion engines.

One ofthe principal objects of the present invention is to provide an internal com- 5 bustion engine having high thermal efii-.

ciency, high mechanical efficiency and high weight efiiciency.

is to provide an improved means and method for supplying liquid fuel to internal combustion engines and more particularly one adapted to cooperate with other features of the design according to the present invention.

Further objects and advantages of the present invention will'be apparent to those skilled in the art from the following description taken in'connection with the accompanying drawings in which Fig. 1 is a front elevation of an engine according'to the present invention, parts being shownin section and parts being omitted for purposes of illustration- I Fig. 2 is a view similar to Fig. 1 and illustrating the same engine but is of a more diagrammatic character and designed particularly to illustrate the flow of fluids while the engine is in operation.

Fig. 3 is adetailed view, parts being shown in section, of a fuel feeding valve and operating apparatus according to the present invention, Fig. 3 illustrating a portion also of a cylinder to which the fuel is delivered by the mechanism shown in the figure.

Fig. 4 is a detailed view of the mechanism utilized according to the present invention for transmitting motion from the governor to the fuel feeding and air throttling mechanisms.

Fig. 5 is a detail of a modification of the mechanism for controlling the flow of air to the compressingv cylinders according to the present invention.

Fig. 6is a detailed diagrammatic view illustrating the arrangement for returning the used fuel oil to the fuel pump.

In the drawings, 20 is an engine shaft to which is connected by the usual crank pitman arrangement piston rods 22, 24, 26 respectively. Each of the rods 22, 24 and 26 has two'pistons affixed thereon, one being a compressor piston and the other a power piston. The compressor piston on rod 22 is indicated at 28. The; piston 28 reciprocates in cylinder, 30, the piston in cylinder 30 being arranged for double acting compression and dividing the cylinder into two compression chambers as more clearly appears from Fig. Another object of the present invention.

2. .Air may be drawn into cylinder 30 direct from the atmosphere but it is preferred that air be taken into cylinder 30 from a supercharger 32 which may be a fan or other rotary low pressure type of air compressor driven from the shaft 20. As illustrated, super-charger 32 is driven from shaft 20 by anordinary belt and pulley drive 34. Air

from supercharger 32 passes to the cylinder 30 through the pipe 36. After compression in the cylinder 30 in the usual manner, air

passes from cylinder 30 through pipe 38.

The pipe 38 preferably contains an intercooler 40. Pipe 38 delivers the air to a higher stage compressor cylinder 42 in which it undergoes another stage of compression. Cylinder 42 is associated with piston rod 26 previously mentioned and contains a compressor piston 44. Piston 44 divides cylinder 42 into two compression chambers. Afterfurther compression inthe cylinder 42, air passes out of this cylinder through pipe 46; Pipe 46 preferably contains an intercooler 48. Pipe 46 delivers the air to the higher stage compressor cylinder 50. Cylinder 50 is associated with the piston rod 24 previously mentioned and contains the compressor piston 52. Piston 52 divides cylinder 50 into two compression chambers. The reciprocation of piston 52 in cylinder 50 further compresses the air. In the arrangement illustrated, cylinder 50 constitutes the third and last stage of compression for the air. However, I do not limit myself to three stages of pistoned compression, since the present invention may be applied to two crank engines as well as to engines having three or more cranks. Preferably, the compression cylinders 30, 42 and 50 are staged and proportioned for equal or minimal com- It will be observed that the cylinder lies intermediate two cylinders, 30 and 42 respectively, which are used for carrying out lower stages of compression of the air which is afterward compressed in cylinder 50. The advantages of placing a higher stage compressor cylinder intermediate two lower stage compressor cylinders will also be enlarged upon later.

Associated with the piston rods 22, 24 and 26 are power cylinders 54, 54, one to each piston rod. Cylinders 54 contain pistons 55, one piston to each cylinder, the cylinders 54 being arranged as illustrated, for double acting operation. In other words, the pistons 55 divide cylinders 54 each into two combustion or expansion chambers. Cylinders 54 are all simple acting as distinguished from the compressor cylinders, which are crosscompounded. Air for supporting combustion in the cylinders 54 is supplied from cylinder 50 through pipe 56. Pipe 56 contains a coil 58 forming part of a recuperator 60 whereby air passing to cylinders 54 is preheated by heat interchange or recuperation with exhaust gases coming from cylinders 54. After the air has been used in cylinders 54 to support combustion of fuel and to develop power in the cylinders by acting against the pistons 55, 55, the products of combustion are exhausted from the cylinders through pipe 62 and passed to the casing of the rpcuperator 60, previously mentioned, where a large part of the heat of the exhaust gases is recovered. The products of combustion may then be exhausted to the atmosphere through pipe 64 which leads from the recuperator 60. If desired, the exhaust gases may be used to drive a gas turbine to assist in operating the supercharger. It will be noted that the compressor cylinders 30, 50 and 42 as well as the power cylinders 54 are all double-acting. I do not limit myself to this, however, as it is within the scope of the present invention to compress the air in the one ends of given cylinders and to use it in the other ends of the same cylinders to produce power by combustion with fuel, all as disclosed in my copending application Ser. l O. 182,967, filed April 11, 1927.

It will be seen from the foregoing description of the arrangements as to the compression cylinders and as to the power cylinders that the power cylinders are all of one size, but the compressor cylinders are of decreasing sizes as the air handled by them increases in pressure. By placing the higher stage compression cylinder intermediate to those of the lower stages space is economized so that the power cylinders ma be set much closer together than would ot erwise be the case. It is evident from Figs. 1 and 2 that if cylinder 42 was set adjacent cylinder 30, the piston rods 22 and 26 would need to be set I er apart than is the casein the arrangement shown for the reason that cylinder 42 would project out and interfere with cylinder 30 if the two were set side by side. While no cam mechanisms are illustrated for operating the valves of the compression or power cylinders, it is assumed that such mechanism is used, it being well-known in the art. Preferably cam mechanism is used for operating the valves not only at both ends of the power cylinders 54, 54, but also those for the compression cylinders 30, 42 and 52. According to the present invention, and as shown in Fig. 1, separate cam shafts 57 and 59 are provided running parallel to the power cylinders 54 and one adjacent the head and the other the crank ends of the cylinders. Shafts 57 and 59 are conveniently driven from the governor shaft 74 which is geared in turn to the engine shaft 20. Preferably the valves of the compressor cylinders 30, 42 and 50 are operated from a single cam shaft 53. Shaft 53 also is driven by gearing from the governor shaft 74. It will be understood however that the valves for the compressor cylinders may be automatic instead of mechanically operated within the present invention.

The compressor cylinders 30, 42 and 50 are provided with water jackets (not shown) arranged in the usual manner. of cooling the air during compression may be used if desired in addition to the water jackets and to the intercoolers previously mentioned. Water for cooling the jackets of compressor cylinders and for the inter coolers and other purposes is supplied preferably by a pump 66, the cylinder of which is preferably mounted directly on the cylinder of one of the air compressors, cylinder 66 be ing illustrated as carried by the intermediate 51 compressor cylinder 42. This method of mounting the cylinder of the water pump 66 is mechanically advantageous in that it enables the piston rod 68 of the pump 66 to be connected rigidly by cross-rod 70 with the cross-head 43 of the compressor cylinder 42. In this way, power for operating the water pump 66 is supplied direct from the piston rod of one of the power cylinders which are mounted in tandem with the compressor cyl I inders, the mechanical efficiency of the transmission from the power cylinder to the water pump 66 therefore being a maximum.

If desired, the power cylinders 54 may be water jacketed, but it is preferred that they be heat insulated by refractory linings except as to the portions of the cylinder against which the piston rings slide. The pistons 55 for power cylinders 54 also preferably have heat insulating refractory coverings except for the portions surround-ed by the piston rings. The use of linings and coverings on the pistons and cylinders as just described forms however, no part of the present invention, being disclosed in prior application Other means" of Henry L. Doherty, Ser. No. 97,164, filed March 25, 1926. Also the use of refractories in double acting cylinders forms no part of the present invention being disclosed in said prior application. I

The fact has been mentioned that the cylinders 30, 42 and 50 are preferably proportioned and arranged for equal or minimal work. of compression; Moreover. the power cylinders 54 are of the same size. It has been found that the compound compression cylinders arranged for minimal work are also those having their reciprocating weights as nearly equal as practicable, assuming the moving parts have been designed in accordance with good practice. The combustion cylinders being of equal size have moving parts of the same weight. The arrangement described of compounded compression cylinders designed for minimal work mounted tandem to simple expansion combustion cylinders produces therefore an engine having a contingent inertia and gravity balance. The balance is improved if both sets of cylinders are double acting. It is preferred also that, when three or a multiple of three cranks are employed that they be set at 120 or at 7 120 divided by a small integer.

der takes its fuel at its head end from pipe 7 6.

It will be seen that the engine according to the present invention and as previously described, involves compressing the air in a plurality of compounded compressing cylinders and thereafter using the air from the highest stage of said compressing cylinders for developing power in a plurality of sim ple expansion power cylinders. It has been found that by compressing the air in a multistage compressor as above described and using the entire output of such compressor for power purposes in a plurahty of expansion power cylinders, high thermal efliciency may be attained together with moderate construction costs and high weight efficiency; The preferred combination is that of compound compression with simple multi-cylinder expansion as combined with other features described herein, such as double-acting tandem cylinders and a particular arrangement of compression cylinders, but in its broadest aspect the present invention is not limited to.

compound or multi-stage compression of air with simplemulti-cylinder expansion.

Fuel for the power cylinders 54 is preferably of the heavy oil type and may be supplied conveniently as shown in Fig. 2 from a fuel pump 72 operated from an eccentric from the governor shaft 74, shaft 74 being geared to the engine shaft'20. Fuel oil is discharged under pressure from the pump barrel 72 through pipes 76, 78. leading respectively to the head ends and crank ends of the power cylinders. Each power cylinand at its crank end from pipe 78. For convenience the pipes 76 and 78 are reduced to and 3.

'77 connecting with pipe 76 and running through the cylinder head block 80 at the head ends of the cylinders 54 as illustrated in section in Fig. 3. The duct in the block or cylinder head at the crank end of cylinders 54 and connecting with pipe 78 is not illustrated in detail, but appears at 79 in the diagrammatic View, Fig. 2. The duct 77 connects with each of the piston or expansion chambers in the head ends of cylinders 54 through fuel ports one of which is illustrated at 82 in Fig. 3. Each of the fuel ports 82 is controlled by a needle valve 86 whosesharply pointed conicalend preferably projects beyond the inner mouth of the port 82 as illustrated at 87 of this arrangement. The flow of fuel oil under pressure into the combustion chambers is always proportional to: p, the axial movement of the valves 86. This would not be the case if'the point of the valve face 86 were arranged to lie at or within the surface of the valve seat-or fuel port;

It is necessary that the flow of oil to cylinder 54 be regulated in accordance with the load so that the engine speed shall remain approximately constant with changes of load. Mechanism for this purpose and according to the present invention is illustrated in Figs. 1 to 4 inclusive and particularly in Figs. 2

In said mechanism, the stems 88 of which the valves 86 form the inner ends are carried out through stuffing boxes in the cylinder heads and connected to levers 90. The connections between stems88 and levers 90 are points intermediate the ends of the levers. At their one ends, levers 90 are loosely fulcrumed on pins 92 affixed to standards 93. At their other ends, levers 90 have pin and slot'connections 94 with stems 95. Stems 95 pass through fixed plates or collars 106. On the opposite side of the plates 106 from the connections 94, stems or rods 95 have fixed thereto collars 108, and springs 110 thrusting against the members 106 and 108 hold levers 9O normally in such position that conical valves 86 are held firmly to their seats 82 so as to prevent the flow of oil. At the ends opposite the connections 94,'stems 95 carry rollers 112. Means are provided for thrusting against the rollers 112 once in each revolution of the engine shaft to overcome the force of springs 110 and to lift the valves 86 to admit fuel oil to the cylinders 54. The preferred means for the; i purpose just mentioned and the one illustrated in the accompanying drawings comprises cams 114 aflixed to shafts 116 driven synchronously from the main engine shaft. 20 and conveniently driven as illustrated by gears 118, 118 on the governor shaft 74. The thrust of cams 114 is transmitted to rollers 112 indirectly, wedge members 120 being interposed between the cams and the rollers. As evident from Fig. 3, the throw of any stem 95 due to a given impulse from its corresponding cam 114, is determined by the relative position of the wedge member 120. If the thicker portion of the wedge member has been inserted between the cam and the roller, the throw or lift of the member 95 and the corresponding lift of the valve 86 will be greater than if the thinner portion of the member 120 were in a position to take the thrust of the cam. The position of wedge members 120 is controlled from the engine governor by means of shafts, one at each end of the cylinders 54 and one of which is illustrated at 122 in Figs. 1 and 3. Means for operating the shafts 122 from the engine governor is illustrated in detail in Fig. 5. The actual movement of the wedge members 120 is caused by eccentrics 124 on the shafts 122.

The fuel supplying and regulating arrangement described above has been found very efiicient and convenient as well as cheap to manufacture. I do not limit myself, however, to the details of the mechanism illustrated, but consider as within the scope of the invention any arrangement for supplying and regulating the flow of fuel to an internal combustion engine having a common fuel pump for a plurality of combustion chambers and governor controlled valves adjacent said chambers for regulating the admission of fuel to the chambers, there being one fuel valve for each chamber and each valve admitting fuel to a single combustion chamber as to which the associated fuel valve is mounted in close proximity.

The heat insulating lining 81 preferably used in the cylinders 54 to cover surfaces exposed to combustion is illustrated at 81 in Fig. 3.

The air supplied to the combustion chambers may, if desired, be maintained at a given weight rate per stroke with varying loads. It is preferred, however, to reduce the weight of air per stroke as the fuel is reduced, at least to a certain extent. In order to coordinate the rate of air used to the rate of fuel used as just mentioned, it is preferred according to the present invention to throttle the air passing to the pistoned compressing cylinders, such as 30, 42 and 50. The air throttle valve for this purpose is illustrated as being placed at 130 in the air line 36 leading from the supercharger 82 to the low pressure cylinder 30. It is desired also that the regulation of the air flow to the compressing cylinders should be performed ordinarily co-ordinately with the regulation of the fuel flow. As illustrated in Figs. 1, 2 and 4, the mechanism for controlling throttle valve 130 includes the shaft 122 previously mentioned. Shaft 122 is rocked from time to time by a linkage 136 operated from the slidable collar 138 of the engine governor, the centrifugal weights of which are illustrated t 140, and which has the shaft 74 previously mentioned. The shaft 122 has a lever 142 fixed thereto. Lever 142 is pivotally connected at its outer end to a rod or link 144 which extends downwardly to a pivotal connection with the operating lever 146 of the throttle valve 130 as shown in Fig. 3. By the arrangement just described it will be obvious that the changes in position of the weights 140 due to changes in speed of the engine will be transmitted to the throttle valve to vary the flow of air at the same time that the fuel is controlled from the governor by changing the positions of wedge members 120 previously mentioned.

A modified arrangement for the operating lever of the throttle valve 130 from rod 142 is illustrated in Fig. 5. In the arrangement illustrated in Fig. 5 the rod 144 carries a cam member 143 at its lower end. No. 143 has an active surface 145 which lies normally in contact with a roller 148 on the end of the lever 146 ofthethrottle valve130. Itis evident from Fig. 5 that any change in the position of the rod 144 will shift the cam member 143 so as to change the position of the valve 130. The cam surface 145 is so designed that the valve 130 will always admit the desired amount of air to the compressing cylinders necessary for the proper governing of the engine speed by the governor. A. spring 147 may be attached to lever 146 to hold roller 148 normally against surface 145.

t will be obvious that the pump 7 2 must have a capacity suiiicient to supply fuel oil to the combustion cylinders at the rate demanded by the maximum load expected to be carried by the engine. At less loads than these the discharge of the fuel pump is therefore greater than necessary at average light loads and would tend to build up excessive pressures on the pipes 7 6 and 78. In order to prevent undue pressures on the apparatus by fuel oil, it is preferred to provide a by-pass valve 96 associated with fuel pump 72. The casing of the by-pass valve 96is connected with the pipe 76 previously mentioned by means of a pipe 98. Pipe 78 also connects into the pipe 98 between pipe and the easing of valve 96. When the pressure in pipes 76 and 78 reaches a predetermined maximum, the valve 96 opens automatically and leaves fuel oil to flow back to the suction side of pump 72 through pipe 102. As illustrated, fresh fuel oil is supplied to the suction side of pump 7 2 through pipe 104, the overflow pipe 102 connecting with pipe 104.

lVhile I have illustrated herein the preferred arrangement of placing the power cylinders farther from the cranks than the compression cylinders, I do not limit myself to this arrangement.

Having thus described my invention, I claim:

1. A compounded compressor having more than two cross-compounded cylinders, said compressor being constructed and arranged so that a cylinder of a given stage of compression is intermediate two cylinders of lower stages of compression.

2. An engine including a plurality of crosscompounded pistoned compressor cylinders, a plurality of simple expansion power cylinders, the pistons of said power cylinders being mounted tandem to those of such compressor cylinders and connected to receive air from combustion from the compressor cylinders, said compressor cylindersbeing so constructed and arranged that a cylinder of a given stage of compression lies intermediate two cylinders of lower stages of compression.

8. In an internal combustion engine, a plurality of compression cylinders, a plurality of expansion cylinders mounted in tandem with said compression cylinders, a cam shaft for the compression cylinders and a second cam shaft for the expansion cylinders.

4. In an internal combustion engine, a plurality of double-acting expansion cylinders, a plurality of double-acting compression cylinders, said compression cylinders being mounted in tandem with the expansion cylinders, a cam shaft for the head ends of said expansion cylinders, a second cam shaft for the crank ends of said expansion cylinders and a third shaft for said compression cylinders.

In testimony whereof I aflix my signature.

ROBERT EARLL BRUCKNER. 

